Can someone tell me how to convert this raw tach time number?

[chriscalandro]

engine_type=ENGINE_LYCOMING
engine_type_uses=ENGINE_TYPE_USES_CHT
horsepower=180
redline_rpm=2700
cruise_rpm=2400
tach_time=615423843
hobbs_time=15425033
rotax_engine_time=0.00

 

[chriscalandro]

That looks about right, and that's what I came up with based on a couple of tests, Thanks!

 

[swatson999]

I thought Tach Time was pulses from the mag...

615423843 revs / 2400 revs/min /60 min/hr = 4273.77 Hrs

?

 

[maartenversteeg]

True, Tach time normally references an engine running time that is normalized to the nominal RPM of the engine, so that when the engine is only run at 60% of its nominal rpm that the tach time only counts 60% of the actual time spend running at that rate. THis matches the idea that tch time is used for engine maintenace and the wear of the engine is related to the number of revolutions that the engine makes